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1. Surface properties of the seas of Titan as revealed by Cassini mission bistatic radar experiments

Author

Valerio Poggiali, Giancorrado Brighi, Alexander G. Hayes, Phil D. Nicholson, Shannon MacKenzie, Daniel E. Lalich, Léa E. Bonnefoy, Kamal Oudrhiri, Ralph D. Lorenz, Jason M. Soderblom, Paolo Tortora, and Marco Zannoni

Subjects
Science
Abstract

Abstract Saturn’s moon Titan was explored by the Cassini spacecraft from 2004 to 2017. While Cassini revealed a lot about this Earth-like world, its radar observations could only provide limited information about Titan’s liquid hydrocarbons seas Kraken, Ligeia and Punga Mare. Here, we show the results of the analysis of the Cassini mission bistatic radar experiments data of Titan’s polar seas. The dual-polarized nature of bistatic radar observations allow independent estimates of effective relative dielectric constant and small-scale roughness of sea surface, which were not possible via monostatic radar data. We find statistically significant variations in effective dielectric constant (i.e., liquid composition), consistent with a latitudinal dependence in the methane-ethane mixing-ratio. The results on estuaries suggest lower values than the open seas, compatible with methane-rich rivers entering seas with higher ethane content. We estimate small-scale roughness of a few millimeters from the almost purely coherent scattering from the sea surface, hinting at the presence of capillary waves. This roughness is concentrated near estuaries and inter-basin straits, perhaps indicating active tidal currents.

Published
2024
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2. Global Lunar Crater Density Using Buffered Nonsparseness Correction

Author

Ya Huei Huang, Christian Riedel, Jason M. Soderblom, Stephanie Brown Krein, Csilla Orgel, Jack W. Conrad, Masatoshi Hirabayashi, and David A. Minton

Subjects
The Moon, Lunar impacts, Planetary surfaces, Surface processes, Planetary geology, Impact gardening, Astronomy, QB1-991
Abstract

The density of craters on a planetary surface directly relates to the age of the surface. As the surface ages, however, craters can be erased by subsequent large impacts via direct overprinting, known as geometric crater obliteration. Such counts become increasingly limited as surfaces become more heavily cratered. Techniques to infer the statistics of the regions obliterated by craters were developed in the past decade. Such techniques, however, have only been used for regional studies. Herein, we present a study of the global density of lunar impact craters ≥20 km in diameter using both traditional crater-counting and buffered nonsparseness correction (BNSC) crater-counting techniques. By comparing the measurements, we quantify the influence of geometric crater obliteration on the visible lunar crater record. Our results reveal that geometric crater obliteration erased up to three-fifths of craters ≥20 km in diameter that formed on the most ancient lunar terrains, whereas younger surfaces, like the Procellarum KREEP Terrane, show little to no evidence of such crater obliteration. The differences in derived crater densities highlight ancient surfaces in which the effects of geometric crater obliteration must be considered to characterize their cratering histories. Furthermore, our results identify the most heavily cratered area on the Moon, a region of the lunar highlands between Smythii basin and the South Pole–Aitken (SPA) basin (Smythii–SPA–Highlands); the number of impacts revealed by the BNSC technique for this region is consistent with estimates derived from the abundance of highly siderophile elements and from modeling crustal porosity.

Published
2024
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3. Modeling the Formation of Selk Impact Crater on Titan: Implications for Dragonfly

Author

Shigeru Wakita, Brandon C. Johnson, Jason M. Soderblom, Jahnavi Shah, Catherine D. Neish, and Jordan K. Steckloff

Subjects
Titan, Saturnian satellites, Planetary surfaces, Impact phenomena, Methane, Astronomy, QB1-991
Abstract

Selk crater is an ∼80 km diameter impact crater on the Saturnian icy satellite Titan. Melt pools associated with impact craters like Selk provide environments where liquid water and organics can mix and produce biomolecules like amino acids. It is partly for this reason that the Selk region has been selected as the area that NASA’s Dragonfly mission will explore and address one of its primary goals: to search for biological signatures on Titan. Here we simulate Selk-sized impact craters on Titan to better understand the formation of Selk and its melt pool. We consider several structures for the icy target material by changing the thickness of the methane clathrate layer, which has a substantial effect on the target thermal structure and crater formation. Our numerical results show that a 4 km diameter impactor produces a Selk-sized crater when 5–15 km thick methane clathrate layers are considered. We confirm the production of melt pools in these cases and find that the melt volumes are similar regardless of methane clathrate layer thickness. The distribution of the melted material, however, is sensitive to the thickness of the methane clathrate layer. In the case of a 10–15 km thick methane clathrate layer, the melt pool appears as a torus-like shape that is a few kilometers deep, and as a shallower layer in the case of a 5 km thick clathrate layer. Melt pools of this thickness may take tens of thousands of years to freeze, allowing more time for complex organics to form.

Published
2023
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11. Cassini Bistatic Radar Observations of Titan's Seas: Results about Dielectric Properties and Capillary Waves Detection

Author

Giancorrado Brighi, Valerio Poggiali, Paolo Tortora, Marco Zannoni, Alexander Hayes, Daniel Lalich, Lea Bonnefoy, Shannon MacKenzie, Phil D Nicholson, Kamal Oudrhiri, Ralph D Lorenz, and Jason M Soderblom

Abstract

Between 2006 and 2016, the Cassini spacecraft carried out 13 bistatic radar observations of the surface of Saturn's largest moon, Titan. Unmodulated right circularly polarized radio signals were transmitted by the spacecraft to the moon’s surface. Cassini’s high gain antenna was pointed so that specular reflections from Titan’s surface were received on Earth. Proper processing of right (RCP) and left circularly polarized (LCP) echoes from the moon can provide information about surface roughness and near-surface relative dielectric constant (ɛr) of the illuminated terrains.During Titan flybys T101, T102, T106, and T124, the track of the bistatic observations crossed the main stable liquid bodies of the north pole of Titan: Ligeia, Kraken, Punga Mare, and their estuaries. Strong and narrowband X-band (λ=3.6 cm) echoes were successfully detected from the seas at the Deep Space Network 70-meter station in Canberra.Reflected spectra feature Dirac-like shapes, with a spectral broadening around 1 Hz and lower bounded by the processing time resolution. Compared to bistatic observations of other planets, this implies unprecedentedly low RMS slope values for Titan’s seas on an effective length-scale of a few meters. Profiles of reflected LCP and RCP power are in general consistent with purely coherent reflections from the Fresnel area around the moving specular point, indicating a very flat surface.In addition, from the circular polarization power ratio, the surface dielectric constant can be derived. This can enrich our current understanding of the chemistry of Titan’s liquid hydrocarbon seas, further constraining their methane-ethane mixing ratio. From Cassini RADAR, VIMS, and ISS, Titan’s seas are expected to be ternary mixtures of methane, ethane and nitrogen (ɛr ≈ 1.6-1.9). From bistatic radar data, significant relative variations in liquid hydrocarbon composition are seen, and an unexpected correlation between the dielectric constant and incidence angle of observation seems to arise. The absolute values of permittivity are somewhat lower than expected.From the computed dielectric constant values, physical optics models are used to constrain the RMS height of the surface. This analysis provides meaningful insights into the presence of small capillary waves in the order of millimeters over the liquid surfaces of Titan, as already detected by Cassini monostatic RADAR.

Published
2023

12. Solid-State Single-Molecule Sensing with the Electronic Life-detection Instrument for Enceladus/Europa (ELIE)

Author

Christopher E. Carr, José L. Ramírez-Colón, Daniel Duzdevich, Sam Lee, Masateru Taniguchi, Takahito Ohshiro, Yuki Komoto, Jason M. Soderblom, and M. T. Zuber

Abstract

Growing evidence of the potential habitability of Ocean Worlds across our Solar System is motivating the advancement of technologies capable of detecting life as we know it – sharing a common ancestry or common physicochemical origin to life on Earth – or don’t know it, representing a distinct genesis event of life quite different than our one known example. Here, we propose the Electronic Life-detection Instrument for Enceladus/Europa (ELIE), a solid-state single-molecule instrument payload that aims to search for life based on the detection of amino acids and informational polymers (IPs) at the parts per billion to trillion level. As a first proof-of- principle in a laboratory environment, we demonstrate single-molecule detection of the amino acid L-proline at a 10 µM concentration in a compact system. Based on ELIE’s solid-state quantum electronic tunneling sensing mechanism, we further propose the quantum property of the HOMO–LUMO gap (energy difference between a molecule’s highest energy occupied molecular orbital and lowest energy unoccupied molecular orbital) as a novel approach to measure amino acid complexity. Finally, we assess the potential of ELIE to discriminate between abiotically and biotically derived (-amino acids in order to reduce false positive risk for life detection. Nanogap technology can also be applied to the detection of nucleobases and short sequences of IPs such as, but not limited to, RNA and DNA. Future missions may utilize ELIE to target preserved biosignatures on the surface of Mars, extant life in its deep subsurface, or life or its biosignatures in the plume, surface, or subsurface of ice moons such as Enceladus or Europa.One Sentence Summary:A solid-state nanogap can determine the abundance distribution of amino acids, detect nucleic acids, and shows potential for detecting life as we know it and life as we don’t.

Published
2022

13. Formation of the Orientale lunar multiring basin

Author

Brandon C. Johnson, David M. Blair, Gareth S. Collins, H. Jay Melosh, Andrew M. Freed, G. Jeffrey Taylor, James W. Head, Mark A. Wieczorek, Jeffrey C. Andrews-Hanna, Francis Nimmo, James T. Keane, Katarina Miljković, Jason M. Soderblom, and Maria T. Zuber

Published
2016
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14. Gravity field of the Orientale basin from the Gravity Recovery and Interior Laboratory Mission

Author

Maria T. Zuber, David E. Smith, Gregory A. Neumann, Sander Goossens, Jeffrey C. Andrews-Hanna, James W. Head, Walter S. Kiefer, Sami W. Asmar, Alexander S. Konopliv, Frank G. Lemoine, Isamu Matsuyama, H. Jay Melosh, Patrick J. McGovern, Francis Nimmo, Roger J. Phillips, Sean C. Solomon, G. Jeffrey Taylor, Michael M. Watkins, Mark A. Wieczorek, James G. Williams, Johanna C. Jansen, Brandon C. Johnson, James T. Keane, Erwan Mazarico, Katarina Miljković, Ryan S. Park, Jason M. Soderblom, and Dah-Ning Yuan

Published
2016
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16. Exploration of Enceladus and Titan: investigating ocean worlds’ evolution and habitability in the Saturn system

Author

Giuseppe Mitri, Jason Barnes, Athena Coustenis, Enrico Flamini, Alexander Hayes, Ralph D. Lorenz, Marco Mastrogiuseppe, Roberto Orosei, Frank Postberg, Kim Reh, Jason M. Soderblom, Christophe Sotin, Gabriel Tobie, Paolo Tortora, Veronique Vuitton, Peter Wurz, ITA, USA, FRA, DEU, CHE, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), University of Idaho [Moscow, USA], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Agenzia Spaziale Italiana (ASI), Department of Astronomy [Ithaca], Cornell University [New York], Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Istituto di Radioastronomia [Bologna] (IRA), Istituto Nazionale di Astrofisica (INAF), Max-Planck-Institut für Kernphysik (MPIK), Max-Planck-Gesellschaft, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Mitri G., Barnes J., Coustenis A., Flamini E., Hayes A., Lorenz R.D., Mastrogiuseppe M., Orosei R., Postberg F., Reh K., Soderblom J.M., Sotin C., Tobie G., Tortora P., Vuitton V., and Wurz P.

Subjects
010504 meteorology & atmospheric sciences, 520 Astronomy, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy and Astrophysics, Ocean world, 620 Engineering, 01 natural sciences, Voyage 2050, 13. Climate action, Space and Planetary Science, 0103 physical sciences, 14. Life underwater, Enceladu, Titan, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

We present a White Paper with a science theme concept of ocean world evolution and habitability proposed in response to ESA’s Voyage 2050 Call with a focus on Titan and Enceladus in the Saturn system. Ocean worlds in the outer Solar System that possess subsurface liquid water oceans are considered to be prime targets for extra-terrestrial life and offer windows into Solar System evolution and habitability. The Cassini-Huygens mission to the Saturn system (2004–2017) revealed Titan with its organic-rich evolving world with terrestrial features and Enceladus with its active aqueous environment to be ideal candidates to investigate ocean world evolution and habitability. Additionally, this White Paper presents a baseline for a multiple flyby mission with a focused payload as an example of how ocean world evolution and habitability in the Saturn system could be investigated building on the heritage of the Cassini-Huygens mission and complementing the recently selected NASA Dragonfly mission.

Published
2021

17. Nitrogen Exsolution and Bubble Formation in Titan's Lakes

Author

Jason M. Soderblom, K. Farnsworth, Jordan K. Steckloff, Vincent Chevrier, Dustin Laxton, Alejandro Soto, and S. Singh

Subjects
symbols.namesake, Geophysics, chemistry, symbols, General Earth and Planetary Sciences, Environmental science, chemistry.chemical_element, Liquid bubble, Titan (rocket family), Nitrogen, Astrobiology
Published
2019

18. Modeling the formation of Menrva impact crater on Titan: Implications for habitability

Author

Brandon C. Johnson, Michael Malaska, Elizabeth A. Silber, E. E. Bjonnes, R. M. C. Lopes, Steve Vance, A. Solomonidou, Jason M. Soderblom, Christophe Sotin, and A. P. Crósta

Subjects
geography, geography.geographical_feature_category, Bedrock, Astronomy and Astrophysics, Context (language use), Astrobiology, Atmosphere, symbols.namesake, Impact crater, Space and Planetary Science, Hypervelocity, symbols, Erosion, Titan (rocket family), Subsurface flow, Geology
Abstract

Titan is unique in the solar system: it is an ocean world, an icy world, an organic world, and has a dense atmosphere. It is a geologically active world as well, with ongoing exogenic processes, such as rainfall, sediment transportation and deposition, erosion, and possible endogenic processes, such as tectonism and cryovolcanism. This combination of an organic and an ocean world makes Titan a prime target for astrobiological research, as biosignatures may be present in its surface, in impact melt deposits and in cryovolcanic flows, as well as in deep ice and water ocean underneath the outer ice shell. Impact craters are important sites in this context, as they may have allowed an exchange of materials between Titan's layers, in particular between the surface, composed of organic sediments over icy bedrock, and the subsurface ocean. It is also possible that impacts may have favored the advance of prebiotic chemical reactions themselves, by providing thermal energy that would allow these reactions to proceed. To investigate possible exchange pathways between the subsurface water ocean and the organic-rich surface, we modeled the formation of the largest crater on Titan, Menrva, with a diameter of ca. 425 km. The premise is that, given a large enough impact event, the resulting crater could breach into Titan's ice shell and reach the subsurface ocean, creating pathways connecting the surface and the ocean. Materials from the deep subsurface ocean, including salts and potential biosignatures of putative subsurface biota, could be transported to the surface. Likewise, atmospherically derived organic surface materials could be directly inserted into the ocean, where they could undergo aqueous hydrolysis to form potential astrobiological building blocks, such as amino acids. To study the formation of a Menrva-like impact crater, we staged numerical simulations using the iSALE-2D shock physics code. We varied assumed ice shell thickness from 50 to 125 km and assumed thermal structure over a range consistent with geophysical data. We analyze the implications and potential contributions of impact cratering as a process that can facilitate the exchange of surface organics with liquid water. Our findings indicate that melt and partial melt of ice took place in the central zone, reaching ca. 65 km depth and ca. 60 km away from the center of the structure. Furthermore, a volume of ca. 102 km3 of ocean water could be traced to depths as shallow as 10 km. These results highlight the potential for a significant exchange of materials from the surface (organics and ice) and the subsurface (water ocean), particularly in the crater's central area. Our studies suggest that large hypervelocity impacts are a viable and likely key mechanism to create pathways between the underground water ocean and Titan's organic-rich surface layer and atmosphere.

Published
2021

19. Lunar Megaregolith Structure Revealed by GRAIL Gravity Data

Author

M. M. Sori, Jason M. Soderblom, Brandon C. Johnson, Sean E. Wiggins, and Kristel Izquierdo

Subjects
Gravity (chemistry), Geophysics, General Earth and Planetary Sciences, Porosity, Ejecta, Geology
Abstract

We use gravity data from NASA's GRAIL mission to characterize the porosity structure of the upper lunar crust. We analyze the gravitational anomalies produced by the porosity of craters with diameters

Published
2021

20. Science Goals and Objectives for the Dragonfly Titan Rotorcraft Relocatable Lander

Author

Simon Stähler, E. R. Stofan, Kevin P. Hand, C. D. Neish, William B. Brinckerhoff, Colin Wilson, Ralph D. Lorenz, Scot Rafkin, R. A. Yingst, Tetsuya Tokano, Kris Zacny, Jani Radebaugh, Christopher P. McKay, Patrick N. Peplowski, Alexander Hayes, Erich Karkoschka, Juan M. Lora, Jorge I. Nunez, Jason W. Barnes, Claire E. Newman, Melissa G. Trainer, Alice Le Gall, A. M. Parsons, Caroline Freissinet, Mark P. Panning, Lynnae C. Quick, David J. Lawrence, Carolyn M. Ernst, Cyril Szopa, Thomas P. Wagner, Jeffrey R. Johnson, Hiroaki Shiraishi, R. S. Miller, Kristin S. Sotzen, Sarah M. Hörst, Shannon MacKenzie, Elizabeth P. Turtle, Morgan L. Cable, Scott L. Murchie, Jason M. Soderblom, Angela Stickle, Department of Physics [Moscow,USA], University of Idaho [Moscow, USA], Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), NASA Goddard Space Flight Center (GSFC), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Astronomy [Ithaca], Cornell University [New York], Morton K. Blaustein Department of Earth and Planetary Sciences [Baltimore], Johns Hopkins University (JHU), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Department of Earth and Planetary Sciences [New Haven], Yale University [New Haven], NASA Ames Research Center (ARC), Planetary Science Institute [Tucson] (PSI), Department of Earth Sciences [London, ON], University of Western Ontario (UWO), Aeolis Research, Department of Geological Sciences [BYU], Brigham Young University (BYU), Southwest Research Institute [Boulder] (SwRI), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), Department of Earth and Planetary Sciences [Cambridge, USA] (EPS), Harvard University [Cambridge], Smithsonian National Air and Space Museum, Smithsonian Institution, Institut für Geophysik und Meteorologie [Köln], Universität zu Köln, NASA Headquarters, Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford [Oxford], Honeybee Robotics Ltd, Institute of Geophysics [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)

Subjects
Aquifer, 01 natural sciences, Mantle (geology), Astrobiology, Pre-biotic astrochemistry, 03 medical and health sciences, symbols.namesake, Extant taxon, Impact crater, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Planetary surfaces, 14. Life underwater, 010303 astronomy & astrophysics, 030304 developmental biology, 0303 health sciences, geography, geography.geographical_feature_category, Habitability, Astronomy and Astrophysics, Prebiotic chemistry, Geophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], symbols, Water ice, Titan (rocket family), Titan, Planetary atmospheres
Abstract

NASA’s Dragonfly mission will send a rotorcraft lander to the surface of Titan in the mid-2030s. Dragonfly's science themes include investigation of Titan’s prebiotic chemistry, habitability, and potential chemical biosignatures from both water-based “life as we know it” (as might occur in the interior mantle ocean, potential cryovolcanic flows, and/or impact melt deposits) and potential “life, but not as we know it” that might use liquid hydrocarbons as a solvent (within Titan’s lakes, seas, and/or aquifers). Consideration of both of these solvents simultaneously led to our initial landing site in Titan’s equatorial dunes and interdunes to sample organic sediments and water ice, respectively. Ultimately, Dragonfly's traverse target is the 80 km diameter Selk Crater, at 7° N, where we seek previously liquid water that has mixed with surface organics. Our science goals include determining how far prebiotic chemistry has progressed on Titan and what molecules and elements might be available for such chemistry. We will also determine the role of Titan’s tropical deserts in the global methane cycle. We will investigate the processes and processing rates that modify Titan’s surface geology and constrain how and where organics and liquid water can mix on and within Titan. Importantly, we will search for chemical biosignatures indicative of past or extant biological processes. As such, Dragonfly, along with Perseverance, is the first NASA mission to explicitly incorporate the search for signs of life into its mission goals since the Viking landers in 1976.

Published
2021

21. Electronic Life-detection Instrument for Enceladus/Europa (ELIE)

Author

Gary Ruvkun, Yuki Komoto, Jack W. Szostak, Takahito Ohshiro, Sam Lee, Masateru Taniguchi, Maria T. Zuber, Jason M. Soderblom, Christopher E. Carr, and Daniel Duzdevich

Subjects
Shell (structure), Transient (oscillation), Enceladus, Life detection, Geology, Astrobiology
Abstract

Habitable regions of Europa may include a subsurface ocean and transient liquid environments within its icy shell. Ocean-surface communication may occur on 1–2 million-year (My) timescales or even ...

Published
2021

22. Callisto: A Guide to the Origin of the Jupiter System

Author

Krishan K. Khurana, Erwan Mazarico, Francis Nimmo, Peter B. James, James W. Head, David J. Smith, Maria T. Zuber, Gregory A. Neumann, Sander Goossens, Jason M. Soderblom, Catherine Johnson, Carol Paty, Mark A. Wieczorek, Antonio Genova, John E. P. Connerney, Michael K. Barker, Louise M. Prockter, and Edward B. Bierhaus

Subjects
Jupiter system, Geology, Astrobiology
Published
2021

23. The Case for Non-Cryogenic Comet Nucleus Sample Return

Author

Scott A. Sandford, Neil Dello Russo, Jason P. Dworkin, Jason M. Soderblom, Jessica M. Sunshine, Samuel Birch, Kenton Fisher, Lisa F. Pace, Steven W. Squyres, Michael J. Mumma, Simon J. Clemett, Nancy L. Chabot, Mathieu Choukroun, Ann N. Nguyen, D. Bodewits, Keiko Nakamura-Messenger, Meenakshi Wadhwa, Alexander Hayes, Julie L. Mitchell, Perry A. Gerakines, Carol A. Raymond, Daniel P. Glavin, Larry R. Nittler, Maitrayee Bose, and Jamie E. Elsila

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Physics, Solar System, Nebula, Comet, FOS: Physical sciences, Early Earth, Astrobiology, Organic molecules, Astrophysics - Solar and Stellar Astrophysics, Planet, Comet nucleus, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

Comets hold answers to mysteries of the Solar System by recording presolar history, the initial states of planet formation and prebiotic organics and volatiles to the early Earth. Analysis of returned samples from a comet nucleus will provide unparalleled knowledge about the Solar System starting materials and how they came together to form planets and give rise to life: 1. How did comets form? 2. Is comet material primordial, or has it undergone a complex alteration history? 3. Does aqueous alteration occur in comets? 4. What is the composition of cometary organics? 5. Did comets supply a substantial fraction of Earth's volatiles? 6. Did cometary organics contribute to the homochirality in life on Earth? 7. How do complex organic molecules form and evolve in interstellar, nebular, and planetary environments? 8. What can comets tell us about the mixing of materials in the protosolar nebula?, Comment: White Paper submitted to the Planetary Science Decadal Survey 2023-2032 reflecting the viewpoints of three New Frontiers comet sample return missions proposal teams, CAESAR, CONDOR, and CORSAIR

Published
2021

24. Ocean Worlds: Science Goals for the Next Decade

Author

Tori M. Hoehler, Wes Patterson, Geoffrey C. Collins, Alyssa Rhoden, Christian Lindensmith, Jason M. Soderblom, Rosaly M. C. Lopes, Laura M. Barge, Kelsi N. Singer, Joseph Westlake, Alexander G. Hayes, Alfred S. McEwen, Morgan L. Cable, Bonnie J. Buratti, Cynthia B. Phillips, Marc Neveu, Terry Hurford, Jeff S. Bowman, Britney E. Schmidt, Chris German, Tom Nordheim, Amanda R. Hendrix, Michael T. Bland, Sona Hosseini, Catherine D. Neish, Steve Vance, Jennifer E.C. Scully, Paul K. Byrne, John F. Cooper, Alex Patthoff, Carly Howett, Serina Diniega, William B. Brinckerhoff, Julie Castillo-Rogez, and Nathalie A. Cabrol

Subjects
Engineering, business.industry, business
Published
2021

25. Ocean Worlds: A Roadmap for Science and Exploration

Author

Joseph Westlake, Shannon MacKenzie, Terry Hurford, Michael T. Bland, Rosaly M. C. Lopes, Laura M. Barge, Pamela Such, Amanda R. Hendrix, Wes Patterson, Chris German, Steve Vance, Jeff S. Bowman, Alfred S. McEwen, Tom Nordheim, Morgan L. Cable, Cynthia B. Phillips, Marc Neveu, Kelsi N. Singer, Tori M. Hoehler, John F. Cooper, William B. Brinckerhoff, Alex Patthoff, Carly Howett, Serina Diniega, Jennifer E.C. Scully, Julie Castillo-Rogez, Sona Hosseini, Catherine D. Neish, Jason M. Soderblom, Nathalie A. Cabrol, Paul K. Byrne, Christian Lindensmith, Britney E. Schmidt, Alexander G. Hayes, Bonnie J. Buratti, Geoffrey C. Collins, and Alyssa Rhoden

Published
2021

26. Investigating the Influences of Crustal Thickness and Temperature on the Uplift of Mantle Materials Beneath Large Impact Craters on the Moon

Author

Carver J. Bierson, Min Ding, Maria T. Zuber, and Jason M. Soderblom

Subjects
Gravity (chemistry), Geophysics, Impact crater, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Geology, Bouguer anomaly, Mantle (geology), Terrane
Abstract

In this work we examine variations in mantle uplift associated with large lunar impact craters and basins between major terranes. We analyze the Bouguer gravity anomalies of 100–650-km diamet...

Published
2021

27. Feasibility Study of a High‐Resolution Shallow Surface Penetration Radar for Space Application

Author

Charles O’Neil, Satheesh Bojja Venkatakrishnan, Rohan Sood, Ivan Galkin, A. G. Hayes, David Braaten, Bodo W. Reinisch, Jie-Bang Yan, Lorenzo Bruzzone, Jason M. Soderblom, H. J. Melosh, John L. Volakis, R. H. Giles, H.-L. Zhang, S. Gogineni, and Paul Song

Subjects
Surface (mathematics), law, Resolution (electron density), General Earth and Planetary Sciences, Penetration (firestop), Electrical and Electronic Engineering, Radar, Condensed Matter Physics, Space (mathematics), Geology, law.invention, Remote sensing
Published
2021

28. Crustal porosity reveals the bombardment history of the Moon

Author

Masatoshi Hirabayashi, Jay Melosh, David A. Minton, Y. H. Huang, and Jason M. Soderblom

Subjects
Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Petrology, Porosity, Geology, Physics::Geophysics
Abstract

Planetary bombardment histories provide critical information regarding the formation and evolution of the Solar System and of the planets within it. These records evidence transient instabilities in the Solar System’s orbital evolution, giant impacts such as the Moon-forming impact, and material redistribution. Such records provide insight into planetary evolution, including the deposition of energy, delivery of materials, and crustal processing, specifically the modification of porosity. Bombardment histories are traditionally constrained from the surface expression of impacts — these records, however, are degraded by various geologic processes. Here we show that the Moon’s porosity contains a more complete record of its bombardment history. We find that the terrestrial planets were subject to double the number of ≥20-km-diameter-crater-forming impacts than are recorded on the lunar highlands, fewer than previously thought to have occurred. We show that crustal porosity doesn’t slowly increase as planets evolve, but instead is generated early in a planet’s evolution when most basins formed and decreases as planets evolve. We show that porosity constrains the relative ages of basins formed early in a planet’s evolution, a timeframe for which little information exists. These findings demonstrate that the Solar System was less violent than previously thought. Fewer volatiles and other materials were delivered to the terrestrial planets, consistent with estimates of the delivery of siderophiles and water to the Moon. High crustal porosity early in the terrestrial planets’ evolution slowed their cooling and enhanced their habitability. Several lunar basins formed early than previously considered, casting doubt on the existence of a late heavy bombardment.

Published
2021

29. New Frontiers Titan Orbiter

Author

Nicholas A. Lombardo, Shawn Brueshaber, Kerry Ramirez, Shannon MacKenzie, Marc Neveu, Alfred S. McEwen, Thomas Cornet, R. T. Desai, Jason D. Hofgartner, Ella Sciamma-O'Brien, Elizabeth P. Turtle, Ed Sittler, Thomas W. Momary, Jani Radebaugh, Stéphane Le Mouélic, Steve Vance, Ari H.D. Koeppel, Paolo Tortora, Ralph D. Lorenz, Patrice Coll, Miriam Rengel, D. Nna-Mvondo, Paul Corlies, Christopher P. McKay, Nicholas A Teanby, L. R. Schurmeier, Tilmann Denk, Gregory A. Neumann, Mark Gurwell, Jason M. Soderblom, Jennifer Hanley, Ajay B. Limaye, Mathieu G.A. Lapotre, Anezina Solomonidou, Daniel Cordier, Sarah A. Fagents, Lori K. Fenton, Conor A. Nixon, Sébastien Lebonnois, Samuel Birch, Chloé Daudon, Sébastien Rodriguez, Michael Heslar, Juan M. Lora, Liliana Lefticariu, Ross A. Beyer, Leonardo Regoli, Chuanfei Dong, E. C. Czaplinski, Farid Salama, Paul O. Hayne, Michael Malaska, A. D. Maue, R. N. Schindhelm, Athena Coustenis, Emilie Royer, Alexander G. Hayes, Catherine D. Neish, Jason W. Barnes, Sandrine Vinatier, Jordan Stekloff, Andrew J. Coates, Erich Karkoschka, Mark Elowitz, J. Michael Battalio, Timothy A. Goudge, Sarah M. Hörst, D. M. Burr, Morgan L. Cable, Shiblee R. Barua, Tuan H. Vu, Rosaly M. C. Lopes, and Rajani D. Dhingra

Subjects
Orbiter, symbols.namesake, law, spacecraft, symbols, decadal survey, White paper, Titan (rocket family), Titan, Geology, Astrobiology, law.invention
Published
2021

30. Science goals and new mission concepts for future exploration of Titan's atmosphere geology and habitability: Titan POlar Scout/orbitEr and In situ lake lander and DrONe explorer (POSEIDON)

Author

Sébastien Rodriguez, Sandrine Vinatier, Daniel Cordier, Gabriel Tobie, Richard K. Achterberg, Carrie M. Anderson, Sarah V. Badman, Jason W. Barnes, Erika L. Barth, Bruno Bézard, Nathalie Carrasco, Benjamin Charnay, Roger N. Clark, Patrice Coll, Thomas Cornet, Athena Coustenis, Isabelle Couturier-Tamburelli, Michel Dobrijevic, F. Michael Flasar, Remco de Kok, Caroline Freissinet, Marina Galand, Thomas Gautier, Wolf D. Geppert, Caitlin A. Griffith, Murthy S. Gudipati, Lina Z. Hadid, Alexander G. Hayes, Amanda R. Hendrix, Ralf Jaumann, Donald E. Jennings, Antoine Jolly, Klara Kalousova, Tommi T. Koskinen, Panayotis Lavvas, Sébastien Lebonnois, Jean-Pierre Lebreton, Alice Le Gall, Emmanuel Lellouch, Stéphane Le Mouélic, Rosaly M. C. Lopes, Juan M. Lora, Ralph D. Lorenz, Antoine Lucas, Shannon MacKenzie, Michael J. Malaska, Kathleen Mandt, Marco Mastrogiuseppe, Claire E. Newman, Conor A. Nixon, Jani Radebaugh, Scot C. Rafkin, Pascal Rannou, Ella M. Sciamma-O’Brien, Jason M. Soderblom, Anezina Solomonidou, Christophe Sotin, Katrin Stephan, Darrell Strobel, Cyril Szopa, Nicholas A. Teanby, Elizabeth P. Turtle, Véronique Vuitton, Robert A. West, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géosciences [UMR_C 6112] (LPG), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, NASA Goddard Space Flight Center (GSFC), Department of Physics and Astronomy [Leicester], University of Leicester, University of Idaho [Moscow, USA], Southwest Research Institute [Boulder] (SwRI), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Planetary Science Institute [Tucson] (PSI), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physical Geography [Utrecht], Utrecht University [Utrecht], Department of Physics [Imperial College London], Imperial College London, Department of Physics [Stockholm], Stockholm University, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Cornell University [New York], Institute of Geological Sciences [Berlin], Department of Earth Sciences [Berlin], Free University of Berlin (FU)-Free University of Berlin (FU), Faculty of Mathematics and Physics [Charles University of Praha], Charles University [Prague] (CU), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Department of Earth and Planetary Sciences [New Haven], Yale University [New Haven], Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Aeolis Research, Department of Geological Sciences [BYU], Brigham Young University (BYU), Space Science and Astrobiology Division at Ames, NASA Ames Research Center (ARC), Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Johns Hopkins University (JHU), School of Earth Sciences [Bristol], University of Bristol [Bristol], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), European Space Agency (ESA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), Université Paris sciences et lettres (PSL), Lancaster University, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
geology, space mission concept, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Habitability, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, orbiter, 7. Clean energy, 01 natural sciences, drones, Orbiter, Poseidon, 0103 physical sciences, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 0105 earth and related environmental sciences, Drones, Earth and Planetary Astrophysics (astro-ph.EP), Atmosphere, 500 Naturwissenschaften und Mathematik::520 Astronomie::520 Astronomie und zugeordnete Wissenschaften, Astronomy and Astrophysics, Geology, FOS: Earth and related environmental sciences, habitability, lake lander, 13. Climate action, Space and Planetary Science, atmosphere, Astrophysics - Instrumentation and Methods for Astrophysics, Titan, Lake lander, Astrophysics - Earth and Planetary Astrophysics
Abstract

In response to ESA Voyage 2050 announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn largest moon Titan. Titan, a "world with two oceans", is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a "heavy" drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan northern latitudes with an orbiter and in situ element(s) would be highly complementary with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration of Titan equatorial regions in the mid-2030s., Comment: arXiv admin note: substantial text overlap with arXiv:1908.01374

Published
2021
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31. The Science Case for a Titan Flagship-class Orbiter with Probes

Author

Conor A. Nixon, Jason M. Soderblom, Xi Zhang, Athena Coustenis, Sébastien Rodriguez, Jani Radebaugh, Jason W. Barnes, Ralph D. Lorenz, Andrew D. Ashton, Mathieu Choukroun, Kathleen Mandt, Adrienn Luspay-Kuti, Elizabeth P. Turtle, Juan M. Lora, Ashley Schoenfeld, Alexander C. Gagnon, Niklas J. T. Edberg, Louis-Alexandre Couston, Stéphane Le Mouélic, Marco Mastrogiuseppe, Gabriel Tobie, Véronique Vuitton, Sandrine Vinatier, Erwan Mazarico, Nathalie Carrasco, X. Sun, Taylor Perron, Darci Snowden, Orenthal J. Tucker, Melissa G. Trainer, Marc Neveu, Luciano Iess, Anezina Solomonidou, Farid Salama, Michael Malaska, Jason D. Hofgartner, Rosaly M. C. Lopes, Nicholas A Teanby, James B. Abshire, Coustenis, Athena, NASA Goddard Space Flight Center (GSFC), Woods Hole Oceanographic Institution (WHOI), University of Idaho [Moscow, USA], PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Swedish Institute of Space Physics [Uppsala] (IRF), and University of Washington [Seattle]

Subjects
Solar System, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], 7. Clean energy, Astrobiology, law.invention, Atmosphere, symbols.namesake, Orbiter, Planet, law, Saturn, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics::Atmospheric and Oceanic Physics, Earth and Planetary Astrophysics (astro-ph.EP), Spacecraft, business.industry, Planetary science, 13. Climate action, Physics::Space Physics, symbols, Environmental science, Astrophysics::Earth and Planetary Astrophysics, Titan (rocket family), business, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We outline a flagship-class mission concept focused on studying Titan as a global system, with particular emphasis on the polar regions. Investigating Titan from the unique standpoint of a polar orbit would enable comprehensive global maps to uncover the physics and chemistry of the atmosphere, and the topography and geophysical environment of the surface and subsurface. The mission includes two key elements: (1) an orbiter spacecraft, which also acts as a data relay, and (2) one or more small probes to directly investigate Titan's seas and make the first direct measurements of their liquid composition and physical environment. The orbiter would carry a sophisticated remote sensing payload, including a novel topographic lidar, a long-wavelength surface-penetrating radar, a sub-millimeter sounder for winds and for mesospheric/thermospheric composition, and a camera and near-infrared spectrometer. An instrument suite to analyze particles and fields would include a mass spectrometer to focus on the interactions between Titan's escaping upper atmosphere and the solar wind and Saturnian magnetosphere. The orbiter would enter a stable polar orbit around 1500 to 1800 km, from which vantage point it would make global maps of the atmosphere and surface. One or more probes, released from the orbiter, would investigate Titan's seas in situ, including possible differences in composition between higher and lower latitude seas, as well as the atmosphere during the parachute descent. The number of probes, as well as the instrument complement on the orbiter and probe, remain to be finalized during a mission study that we recommend to NASA as part of the NRC Decadal Survey for Planetary Science now underway, with the goal of an overall mission cost in the "small flagship" category of ~$2 bn. International partnerships, similar to Cassini-Huygens, may also be included for consideration., 13 pages, white paper submitted to the NRC Decadal Survey for Planetary Science and Astrobiology

Published
2020

32. A new digital terrain model of the Huygens landing site on Saturn's largest moon, Titan

Author

C. Daudon, B. Grieger, R. L. Kirk, Jason M. Soderblom, Elpitha Howington-Kraus, A. Escalante López, Sebastien Rodriguez, Antoine Lucas, Erich Karkoschka, S. Jacquemoud, Marithelma Costa, J. T. Perron, Institut de Physique du Globe de Paris (IPGP), and Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
010504 meteorology & atmospheric sciences, lcsh:Astronomy, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Environmental Science (miscellaneous), 01 natural sciences, Astrobiology, lcsh:QB1-991, symbols.namesake, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, topography, 0103 physical sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Digital elevation model, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 010303 astronomy & astrophysics, DISR, 0105 earth and related environmental sciences, lcsh:QE1-996.5, rivers, DTM, lcsh:Geology, 13. Climate action, Huygens, symbols, General Earth and Planetary Sciences, Titan, Titan (rocket family), Geology
Abstract

International audience; A new digital terrain model of the Huygens landing 1 site on Saturn's largest moon • We create a new digital terrain model (DTM) of the Huygens landing site that 14 offers the best available resolution of river valleys on Titan. 15 • The complexity of the data set requires a tailor-made reconstruction procedure 16 that is detailed. 17 • The workflow uses reprocessed Huygens/DISR images and an automated shape-18 from-motion algorithm to improve an earlier DTM. Abstract 20 River valleys have been observed on Titan at all latitudes by the Cassini-Huygens 21 mission. Just like water on Earth, liquid methane carves into the substrate to form a com-22 plex network of rivers, particularly stunning in the images acquired near the equator by 23 the Huygens probe. To better understand the processes at work that form these land-24 scapes, one needs an accurate digital terrain model (DTM) of this region. The first and 25 to date the only existing DTM of the Huygens landing site was produced by the United 26 States Geological Survey (USGS) from high-resolution images acquired by the DISR (De-27 scent Imager/Spectral Radiometer) cameras onboard the Huygens probe and using the 28 SOCET SET photogrammetric software. However, this DTM displays inconsistencies, 29 primarily due to non optimal viewing geometries and to the poor quality of the origi-30 nal data, unsuitable for photogrammetric reconstruction. We investigate a new approach, 31 benefiting from a recent reprocessing of the DISR images correcting both the radiomet-32 ric and geometric distortions. For the DTM reconstruction, we use MicMac, a photogram-33 metry software based on automatic open-source shape-from-motion algorithms. To over-34 come challenges such as data quality and image complexity (unusual geometric config-35 uration), we developed a specific pipeline that we detailed and documented in this ar-36 ticle. In particular, we take advantage of geomorphic considerations to assess ambigu-37 ity on the internal calibration and the global orientation of the stereo model. Besides the 38 novelty in this approach, the resulting DTM obtained offers the best spatial sampling 39 of Titan's surface available and a significant improvement over the previous results. 40

Published
2020

34. Methane-saturated Layers Limit the Observability of Impact Craters on Titan

Author

Shigeru Wakita, Brandon C. Johnson, Jason M. Soderblom, Jahnavi Shah, and Catherine D. Neish

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Geophysics, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

As the only icy satellite with a thick atmosphere and liquids on its surface, Titan represents a unique end-member to study the impact cratering process. Unlike craters on other Saturnian satellites, Titan's craters are preferentially located in high-elevation regions near the equator. This led to the hypothesis that the presence of liquid methane in Titan's lowlands affects crater morphology, making them difficult to identify. This is because surfaces covered by weak fluid-saturated sediment limit the topographic expression of impact craters, as sediment moves into the crater cavity shortly after formation. Here we simulate crater-forming impacts on Titan's surface, exploring how a methane-saturated layer overlying a methane-clathrate layer affects crater formation. Our numerical results show that impacts form smaller craters in a methane-clathrate basement than a water-ice basement, due to the differences in strength. We find that the addition of a methane-saturated layer atop this basement reduces crater depths and influences crater morphology. The morphology of impact craters formed in a thin methane-saturated layer are similar to those in a "dry" target, but a thick saturated layer produces an impact structure with little to no topography. A thick methane-saturated layer (thicker than 40% of the impactor diameter) could explain the dearth of craters in the low-elevation regions on Titan., Comment: 33 pages, 12 figures, accepted for publication in PSJ

Published
2022

35. Constraints on Lunar Crustal Porosity From the Gravitational Signature of Impact Craters

Author

Francis Nimmo, Min Ding, Carver J. Bierson, Maria T. Zuber, Jason M. Soderblom, and Colleen Milbury

Subjects
010504 meteorology & atmospheric sciences, Geophysics, 010502 geochemistry & geophysics, 01 natural sciences, Gravity anomaly, Gravitation, Impact crater, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Porosity, Signature (topology), Geology, 0105 earth and related environmental sciences
Published
2018

36. Reexamination of Early Lunar Chronology With GRAIL Data: Terranes, Basins, and Impact Fluxes

Author

Jeffrey C. Andrews-Hanna, Alexander J. Evans, Jason M. Soderblom, Sean C. Solomon, James W. Head, and Maria T. Zuber

Subjects
010504 meteorology & atmospheric sciences, Geochemistry, 01 natural sciences, Geophysics, Geology of the Moon, Impact crater, Space and Planetary Science, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences, Chronology, Terrane
Published
2018

37. Isostatic Compensation of the Lunar Highlands

Author

Jason M. Soderblom, Mark A. Wieczorek, Peter B. James, Michael M. Sori, Brandon C. Johnson, Maria T. Zuber, and Sean C. Solomon

Subjects
Gravity (chemistry), 010504 meteorology & atmospheric sciences, Equipotential surface, Elevation, 010502 geochemistry & geophysics, Geodesy, 01 natural sciences, Geophysics, Planetary science, Geology of the Moon, Space and Planetary Science, Geochemistry and Petrology, Lithosphere, Isostasy, Earth and Planetary Sciences (miscellaneous), Altimeter, Geology, 0105 earth and related environmental sciences
Abstract

The lunar highlands are isostatically compensated at large horizontal scales, but the specific compensation mechanism has been difficult to identify. With topographic data from the Lunar Orbiter Laser Altimeter and gravity data from the Gravity Recovery and Interior Laboratory, we investigate support of highland topography. Poor correlation between crustal density and elevation shows that Pratt compensation is not important in the highlands. Using spectrally weighted admittance, we compared observed values of geoid-to-topography ratio (GTR) with those predicted by isostatic models. Observed GTRs are 25.8 +7.5-5.7 m/km for the nearside highlands and 39.3 +5.7-6.2 m/km for the farside highlands. These values are not consistent with flexural compensation of long-wavelength topography or Airy isostasy defined under an assumption of equal mass in crustal columns. Instead, the observed GTR values are consistent with models of Airy compensation in which isostasy is defined under a requirement of equal pressures at equipotential surfaces at depth. The gravity and topography data thus reveal that long-wavelength topography on the Moon is most likely compensated by variations in crustal thickness, implying that highland topography formed early in lunar history before the development of a thick elastic lithosphere.

Published
2018

38. The Role of Breccia Lenses in Regolith Generation From the Formation of Small, Simple Craters: Application to the Apollo 15 Landing Site

Author

H. J. Melosh, Masatoshi Hirabayashi, David A. Minton, Bryan A. Howl, Caleb I. Fassett, and Jason M. Soderblom

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), SIMPLE (dark matter experiment), Lunar craters, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Blanketing, Radius, 01 natural sciences, Regolith, Astrobiology, Geophysics, Impact crater, Space and Planetary Science, Geochemistry and Petrology, 0103 physical sciences, Breccia, Earth and Planetary Sciences (miscellaneous), Ejecta, 010303 astronomy & astrophysics, Geology, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences
Abstract

Impact cratering is likely a primary agent of regolith generation on airless bodies. Regolith production via impact cratering has long been a key topic of study since the Apollo era. The evolution of regolith due to impact cratering, however, is not well understood. A better formulation is needed to help quantify the formation mechanism and timescale of regolith evolution. Here, we propose an analytically derived stochastic model that describes the evolution of regolith generated by small, simple craters. We account for ejecta blanketing as well as regolith infilling of the transient crater cavity. Our results show that the regolith infilling plays a key role in producing regolith. Our model demonstrates that, because of the stochastic nature of impact cratering, the regolith thickness varies laterally, which is consistent with earlier work. We apply this analytical model to the regolith evolution at the Apollo 15 site. The regolith thickness is computed considering the observed crater size-frequency distribution of small, simple lunar craters (< 381 m in radius for ejecta blanketing and < 100 m in radius for the regolith infilling). Allowing for some amount of regolith coming from the outside of the area, our result is consistent with an empirical result from the Apollo 15 seismic experiment. Finally, we find that the timescale of regolith growth is longer than that of crater equilibrium, implying that even if crater equilibrium is observed on a cratered surface, it is likely the regolith thickness is still evolving due to additional impact craters., 32 pages, 13 figures, 2 tables, and accepted for publication in JGR-Planets

Published
2018

39. Tracking Short-term Variations in the Haze Distribution of Titan’s Atmosphere with SINFONI VLT

Author

Juan M. Lora, Fiona Nichols-Fleming, Alexander G. Hayes, Jason M. Soderblom, Patricio Rojo, Paul Corlies, Sebastien Rodriguez, Máté Ádámkovics, and Elizabeth P. Turtle

Subjects
Haze, Distribution (number theory), Astronomy and Astrophysics, Tracking (particle physics), Atmospheric sciences, Term (time), Atmosphere, symbols.namesake, Geophysics, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), symbols, Environmental science, Titan (rocket family)
Abstract

While it has long been known that Titan’s haze and atmosphere are dynamic on seasonal timescales, recent results have revealed that they also exhibit significant subseasonal variations. Here, we report on observations of Titan acquired over an eight-month period between 2014 April and 2015 March with the Spectrograph for Integral Field Observations in the Near Infrared instrument on the Very Large Telescope using adaptive optics. These observations have an average five-day cadence, permitting interrogation of the short-period variability of Titan’s atmosphere. Disk-resolved spectra in the H and K bands (1.4–2.4 μm) were analyzed with the PyDISORT radiative transfer model to determine the spatial distribution and variation of stratospheric haze opacity over subseasonal timescales. We observed a uniform decrease in haze opacity at 20°N and an increase in haze opacity at 250–300°E and ∼40°N over the span of our observations. Globally, we found variations on the order of 5%–10% on timescales of weeks, as well as a steady, global increase in the amount of haze over timescales of months. The observed variations in haze opacity over the short timescales of our observations were of similar magnitude to long-period variations attributed to seasonal variation, suggesting rapid dynamical processes that may take part in the distribution of hazes in Titan’s atmosphere.

Published
2021

40. Geomorphology of comet 67P/Churyumov–Gerasimenko

Author

Yanga R. Fernandez, N. W. Kutsop, Holger Sierks, Dennis Bodewits, Humberto Campins, Y. Tang, Jason M. Soderblom, Samuel Birch, R. de Freitas Bart, Steven W. Squyres, R. L. Kirk, Alexander Hayes, and J.-B. Vincent

Subjects
Physics, 010504 meteorology & atmospheric sciences, Space and Planetary Science, 0103 physical sciences, Comet, Astronomy and Astrophysics, 010303 astronomy & astrophysics, 01 natural sciences, 0105 earth and related environmental sciences, Astrobiology
Published
2017

41. Titan as Revealed by the Cassini Radar

Author

Federico Tosi, L. A. Soderblom, Charles Elachi, G. Mitri, Zhimeng Zhang, Alexander G. Hayes, S. D. Wall, Jason M. Soderblom, P. Paillou, Elizabeth P. Turtle, Richard West, R. L. Kirk, Gian Gabriele Ori, Tom G. Farr, Howard A. Zebker, Claudia Notarnicola, Paul Corlies, M. Mastroguiseppe, Jason W. Barnes, Antoine Lucas, K. L. Mitchell, Jason D. Hofgartner, Bryan Stiles, Athena Coustenis, Valerio Poggiali, A. Solomonidou, Cyril Grima, Roberto Orosei, O. Karatekin, E. R. Stofan, Jani Radebaugh, Spd Birch, Rmc Lopes, Domenico Casarano, A. LeGall, P Encrenaz, Michael Malaska, Charles A. Wood, Flora Paganelli, Douglas J. Hemingway, Daniele Riccio, Sebastien Rodriguez, Catherine D. Neish, M. A. Janssen, R. D. Lorenz, Paul Ries, Jonathan I. Lunine, Ashley Schoenfeld, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Astronomy [Ithaca], Cornell University, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), University of Arizona, Lunar and Planetary Laboratory [Tucson] (LPL), Università degli Studi di Roma 'La Sapienza' [Rome], Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Florida Institute of Technology [Melbourne], Institut de génétique humaine (IGH), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Service de cardiologie [Hôpital Nord - APHM], Aix Marseille Université (AMU)-Assistance Publique - Hôpitaux de Marseille (APHM)- Hôpital Nord [CHU - APHM], Observatoire Bordeaux, Université Sciences et Technologies - Bordeaux 1, Department of Geological Sciences [BYU], Brigham Young University (BYU), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Department of Earth, Planetary and Space Sciences [Los Angeles] (EPSS), University of California [Los Angeles] (UCLA), University of California-University of California, Proxemy Research Inc, Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Wheeling Jesuit University, Department of Electrical Engineering [Stanford], Stanford University [Stanford], Istituto di Ricerca per la Protezione Idrogeologica [Bari] (IRPI), Consiglio Nazionale delle Ricerche [Roma] (CNR), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Swedish Institute of Space Physics [Uppsala] (IRF), Miller Institute for Basic Research in Science, University of California [Berkeley], Royal Observatory of Belgium [Brussels], Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), International Research School of Planetary Sciences [Pescara] (IRSPS), Università degli studi 'G. d'Annunzio' Chieti-Pescara [Chieti-Pescara] (Ud'A), Istituto di Fisica dello Spazio Interplanetario (IFSI), Consiglio Nazionale delle Ricerche (CNR), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [London, ON], University of Western Ontario (UWO), Institute for Earth Observation [Bolzano], EURAC Research, Search for Extraterrestrial Intelligence Institute (SETI), ASP 2019, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), European Space Astronomy Centre (ESAC), European Space Agency (ESA), Smithsonian National Air and Space Museum, Smithsonian Institution, Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Planetary Science Institute [Tucson] (PSI), Department of Physics [Moscow,USA], University of Idaho [Moscow, USA], Istituto di Ricerca per la Protezione Idrogeologica [Padova] (IRPI), Institute of Geophysics [Austin] (IG), University of Texas at Austin [Austin], Istituto di Radioastronomia (IRA), Dipartimento di Ingegneria Elettrica e delle Tecnologie dell'Informazione [Napoli] (DIETI), Università degli studi di Napoli Federico II, Cornell University [New York], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], European Academy Bozen/Bolzano (EURAC), Stanford University, Royal Observatory of Belgium [Brussels] (ROB), Istituto di Radioastronomia [Bologna] (IRA), Lopes, R. M. C., Wall, S. D., Elachi, C., Birch, S. P. D., Corlies, P., Coustenis, A., Hayes, A. G., Hofgartner, J. D., Janssen, M. A., Kirk, R. L., Legall, A., Lorenz, R. D., Lunine, J. I., Malaska, M. J., Mastroguiseppe, M., Mitri, G., Neish, C. D., Notarnicola, C., Paganelli, F., Paillou, P., Poggiali, V., Radebaugh, J., Rodriguez, S., Schoenfeld, A., Soderblom, J. M., Solomonidou, A., Stofan, E. R., Stiles, B. W., Tosi, F., Turtle, E. P., West, R. D., Wood, C. A., Zebker, H. A., Barnes, J. W., Casarano, D., Encrenaz, P., Farr, T., Grima, C., Hemingway, D., Karatekin, O., Lucas, A., Mitchell, K. L., Ori, G., Orosei, R., Ries, P., Riccio, D., Soderblom, L. A., Zhang, Z., ITA, USA, FRA, and Hôpital Nord [CHU - APHM]-Assistance Publique - Hôpitaux de Marseille (APHM)-Aix Marseille Université (AMU)

Subjects
Exploration of Saturn, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], 01 natural sciences, Liquid methane, law.invention, Astrobiology, symbols.namesake, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, law, 0103 physical sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Radar, Enceladus, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, Cassini, radar, Titan, Planetary science, 13. Climate action, Space and Planetary Science, symbols, Titan (rocket family), Geology
Abstract

International audience; Titan was a mostly unknown world prior to the Cassini spacecraft’s arrival in July 2004. We review the major scientific advances made by Cassini’s Titan Radar Mapper (RADAR) during 13 years of Cassini’s exploration of Saturn and its moons. RADAR measurements revealed Titan’s surface geology, observed lakes and seas of mostly liquid methane in the polar regions, measured the depth of several lakes and seas, detected temporal changes on its surface, and provided key evidence that Titan contains an interior ocean. As a result of the Cassini mission, Titan has gone from an uncharted world to one that exhibits a variety of Earth-like geologic processes and surface-atmosphere interactions. Titan has also joined the ranks of “ocean worlds” along with Enceladus and Europa, which are prime targets for astrobiological research.

Published
2019

42. The Cassini VIMS archive of Titan: From browse products to global infrared color maps

Author

Jason W. Barnes, S. Le Mouélic, Jason M. Soderblom, Benoît Seignovert, Sebastien Rodriguez, Roger N. Clark, Philip D. Nicholson, Robert H. Brown, Thomas Cornet, B. J. Buratti, Jérémie Lasue, V. Pasek, Kevin H. Baines, Christophe Sotin, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM), Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Moscow,USA], University of Idaho [Moscow, USA], Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), California Institute of Technology (CALTECH), Department of Astronomy [Ithaca], Cornell University [New York], Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Massachusetts Institute of Technology (MIT), Microenvironment, Cell Differentiation, Immunology and Cancer (MICMAC), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Laboratoire SITI [CHU Rennes], Etablissement français du sang [Rennes] (EFS Bretagne)-CHU Pontchaillou [Rennes], Université de Perpignan Via Domitia (UPVD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Universität Bern- University of Bern [Bern], Partenaires INRAE, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), DLR Institute of Planetary Research, German Aerospace Center (DLR), US Geological Survey [Denver], United States Geological Survey [Reston] (USGS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Brightness, Haze, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Multispectral image, FOS: Physical sciences, 01 natural sciences, law.invention, law, 0103 physical sciences, Radiative transfer, Imaging science, Radar, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Remote sensing, Earth and Planetary Astrophysics (astro-ph.EP), Spectrometer, Pixel, Astronomy and Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Geology, Astrophysics - Earth and Planetary Astrophysics
Abstract

International audience; We have analyzed the complete Visual and Infrared Mapping Spectrometer (VIMS) data archive of Titan. Our objective is to build global surface cartographic products, by combining all the data gathered during the 127 targeted flybys of Titan into synthetic global maps interpolated on a grid at 32 pixels per degree (∼1.4 km/pixel at the equator), in seven infrared spectral atmospheric windows. Multispectral summary images have been computed for each single VIMS cube in order to rapidly identify their scientific content and assess their quality. These summary images are made available to the community on a public website (vims.univ-nantes.fr). The global mapping work faced several challenges due to the strong absorbing and scattering effects of the atmosphere coupled to the changing observing conditions linked to the orbital tour of the Cassini mission. We determined a surface photometric function which accounts for variations in incidence, emergence and phase angles, and which is able to mitigate brightness variations linked to the viewing geometry of the flybys. The atmospheric contribution has been reduced using the subtraction of the methane absorption band wings, considered as proxies for atmospheric haze scattering. We present a new global three color composite map of band ratios (red: 1.59/1.27 µm; green: 2.03/1.27 µm; blue: 1.27/1.08 µm), which has also been empirically corrected from an airmass (the solar photon path length through the atmosphere) dependence. This map provides a detailed global color view of Titan's surface partially corrected from the atmosphere and gives a global insight of the spectral variability, with the equatorial dunes fields appearing in brownish tones, and several occurrences of bluish tones localized in areas such as Sinlap, Menvra and Selk craters. This kind of spectral map can serve as a basis for further regional studies and comparisons with radiative transfer outputs, such as surface albedos, and other additional data sets acquired by the Cassini Radar (RADAR) and Imaging Science Subsystem (ISS) instruments.

Published
2019

43. The NASA Roadmap to Ocean Worlds

Author

Cynthia B. Phillips, Marc Neveu, Kelsi N. Singer, G. Wesley Patterson, Michael T. Bland, Steven D. Vance, D. Alex Patthoff, Amanda R. Hendrix, Terry Hurford, Tom Nordheim, Laura M. Barge, Alfred S. McEwen, Tori M. Hoehler, Sona Hosseini, Catherine D. Neish, William B. Brinckerhoff, Jason M. Soderblom, Bonnie J. Buratti, Carly Howett, Serina Diniega, Morgan L. Cable, Julie Castillo-Rogez, Geoffrey C. Collins, Alyssa Rhoden, Britney E. Schmidt, Jeff S. Bowman, Alexander G. Hayes, and Christopher R. German

Subjects
Engineering, Outer planets, 010504 meteorology & atmospheric sciences, United States National Aeronautics and Space Administration, Oceans and Seas, Planets, Astronomy & Astrophysics, 01 natural sciences, GeneralLiterature_MISCELLANEOUS, Enceladus, 0103 physical sciences, Exobiology, Triton, 010303 astronomy & astrophysics, Life Below Water, 0105 earth and related environmental sciences, business.industry, Habitability, Geology, Agricultural and Biological Sciences (miscellaneous), Data science, United States, Roadmap, Geochemistry, Forum Articles, Space and Planetary Science, Extraterrestrial life, business, Europa, NASA, Titan, Astronomical and Space Sciences
Abstract

In this article, we summarize the work of the NASA Outer Planets Assessment Group (OPAG) Roadmaps to Ocean Worlds (ROW) group. The aim of this group is to assemble the scientific framework that will guide the exploration of ocean worlds, and to identify and prioritize science objectives for ocean worlds over the next several decades. The overarching goal of an Ocean Worlds exploration program as defined by ROW is to “identify ocean worlds, characterize their oceans, evaluate their habitability, search for life, and ultimately understand any life we find.” The ROW team supports the creation of an exploration program that studies the full spectrum of ocean worlds, that is, not just the exploration of known ocean worlds such as Europa but candidate ocean worlds such as Triton as well. The ROW team finds that the confirmed ocean worlds Enceladus, Titan, and Europa are the highest priority bodies to target in the near term to address ROW goals. Triton is the highest priority candidate ocean world to target in the near term. A major finding of this study is that, to map out a coherent Ocean Worlds Program, significant input is required from studies here on Earth; rigorous Research and Analysis studies are called for to enable some future ocean worlds missions to be thoughtfully planned and undertaken. A second finding is that progress needs to be made in the area of collaborations between Earth ocean scientists and extraterrestrial ocean scientists.

Published
2019

44. Observational Evidence for Summer Rainfall at Titan's North Pole

Author

Jason W. Barnes, P. D. Nicholson, Sebastien Rodriguez, Bonnie J. Burrati, Ralf Jauman, Elizabeth P. Turtle, Christophe Sotin, Kevin H. Baines, Don E. Jennings, Jason Perry, Roger N. Clark, Rajani D. Dhingra, Jason M. Soderblom, V. Cottini, Stéphane Le Mouélic, Robert H. Brown, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Cornell University [New York], MIT, Earth Atmospher & Planetary Sci, 77 Massachusetts Ave, Cambridge, MA 02139 USA, DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), and NASA Goddard Space Flight Center (GSFC)

Subjects
North pole, ComputerSystemsOrganization_COMPUTERSYSTEMIMPLEMENTATION, 010504 meteorology & atmospheric sciences, GeneralLiterature_INTRODUCTORYANDSURVEY, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], ComputerApplications_COMPUTERSINOTHERSYSTEMS, 010502 geochemistry & geophysics, 01 natural sciences, Observational evidence, symbols.namesake, Geophysics, Climatology, symbols, General Earth and Planetary Sciences, Titan (rocket family), Geology, 0105 earth and related environmental sciences
Abstract

International audience; Methane rain on Saturn's moon Titan makes it the only place, other than Earth, where rain interacts with the surface. When and where that rain wets the surface changes seasonally in ways that remain poorly understood. Here we report the discovery of a bright ephemeral feature covering an area of 120,000 km 2 near Titan's north pole in observations from Cassini's near-infrared instrument, Visual and Infrared Mapping Spectrometer on 7 June 2016. Based on the overall brightness, spectral characteristics, and geologic context, we attribute this new feature to specular reflections from a rain-wetted solid surface like those off of a sunlit wet sidewalk. The reported observation is the first documented rainfall event at Titan's north pole and heralds the arrival of the northern summer (through climatic evidence), which has been delayed relative to model predictions. This detection helps constrain Titan's seasonal change and shows that the "wet-sidewalk effect can be used to identify other rain events." Plain Language Summary Cassini arrived in the Saturnian system in the southern summers of 2004. As expected, the Cassini team observed cloud cover, storms, and precipitation on the south pole. Like Earth, Titan has an axial tilt (27 •) and its seasons vary over its year (30 Earth years). Ever since this shift in season began, the Cassini team eagerly waited for observations indicating cloud cover and precipitation that went missing from the northern latitudes. Our rainfall observation at the north pole is a major finding for two important reasons. First, this discovery observation heralds the much awaited arrival of the north polar summer rainstorms on Titan. This atmospheric phenomenon has been delayed compared to the theoretical predictions and was perplexing Titan researchers and climate modelers especially because the north pole hosts most of Titan's lakes and seas. Second, it is extremely difficult to detect rainfall events on Titan due to its thick atmospheric haze and very limited opportunities to view the surface (and its changes). We have used a novel phenomenon-the smoothening of a previously dry, rough surface by a thin layer of fluid after rainfall, similar to a wet sidewalk-as evidence for rainfall events on the surface of Titan.

Published
2019

45. Subsurface morphology and scaling of lunar impact basins

Author

Mark A. Wieczorek, Katarina Miljković, Gregory A. Neumann, Jason M. Soderblom, Brandon C. Johnson, Gareth S. Collins, and Maria T. Zuber

Subjects
Solar System, 010504 meteorology & atmospheric sciences, Flux, Geophysics, Structural basin, Present day, 01 natural sciences, Billion years, Impact crater, Gravitational field, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Terrestrial planet, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Abstract

Impact bombardment during the first billion years after the formation of the Moon produced at least several tens of basins. The Gravity Recovery and Interior Laboratory (GRAIL) mission mapped the gravity field of these impact structures at significantly higher spatial resolution than previous missions, allowing for detailed subsurface and morphological analyses to be made across the entire globe. GRAIL-derived crustal thickness maps were used to define the regions of crustal thinning observed in centers of lunar impact basins, which represents a less unambiguous measure of a basin size than those based on topographic features. The formation of lunar impact basins was modeled numerically by using the iSALE-2D hydrocode, with a large range of impact and target conditions typical for the first billion years of lunar evolution. In the investigated range of impactor and target conditions, the target temperature had the dominant effect on the basin subsurface morphology. Model results were also used to update current impact scaling relationships applicable to the lunar setting (based on assumed target temperature). Our new temperature-dependent impact-scaling relationships provide estimates of impact conditions and transient crater diameters for the majority of impact basins mapped by GRAIL. As the formation of lunar impact basins is associated with the first approximately 700 Myr of the solar system evolution when the impact flux was considerably larger than the present day, our revised impact scaling relationships can aid further analyses and understanding of the extent of impact bombardment on the Moon and terrestrial planets in the early solar system.

Published
2016

46. Interactions between complex craters and the lunar crust: Analysis using GRAIL data

Author

Carver J. Bierson, Colleen Milbury, Roger J. Phillips, J. Besserer, Maria T. Zuber, Jason M. Soderblom, James T. Keane, and Francis Nimmo

Subjects
Lunar geologic timescale, Gravity (chemistry), 010504 meteorology & atmospheric sciences, Lunar mare, Crust, Geophysics, 01 natural sciences, Geology of the Moon, Impact crater, Space and Planetary Science, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), 010303 astronomy & astrophysics, Geology, Bouguer anomaly, 0105 earth and related environmental sciences, Terrane
Abstract

A high-resolution gravity map over the entire lunar surface has been derived from data acquired by the Gravity Recovery and Interior Laboratory (GRAIL) mission. Soderblom et al. (2015) showed that crater Bouguer gravity anomalies scale with crater diameter and porosity for craters in the lunar highlands. Here we extend this study globally, examining complex craters in each of the three lunar terranes: highlands, maria, and the South Pole-Aitken basin. We find that craters within South Pole-Aitken basin and in the lunar maria have statistically different Bouguer anomalies from those in the lunar highlands. These differences are best explained by differences in crustal porosity among the three terranes. Though there is still much unresolved scatter in the data, we find that no other lunar material properties (crustal thickness, density gradient, etc.) are able to improve our model fit to the data.

Published
2016

47. Titan’s 'Magic Islands': Transient features in a hydrocarbon sea

Author

Ralph D. Lorenz, Jason M. Soderblom, Claudia Notarnicola, Marco Mastrogiuseppe, Jonathan I. Lunine, Alexander G. Hayes, Jason D. Hofgartner, Michael Malaska, and Howard A. Zebker

Subjects
Sea level change, geological processes, 010504 meteorology & atmospheric sciences, radar observations, Titan, Ephemeral key, Astronomy and Astrophysics, 01 natural sciences, Seafloor spreading, Astrobiology, Radar observations, symbols.namesake, Space and Planetary Science, 0103 physical sciences, symbols, Titan (rocket family), 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Abstract

The region of Titan’s hydrocarbon sea, Ligeia Mare, where transient bright features were previously discovered, was anomalously bright in the first of two more recent Cassini RADAR observations but not the second. Another transient bright feature in a different region of Ligeia Mare was also discovered in the first of the new observations. Here we present all the high-resolution observations of the regions containing these transient features and the quantitative constraints that we derived from them. We argue that these features are unlikely to be SAR image artifacts or permanent geophysical structures and thus their appearance is the result of ephemeral phenomena on Titan. We find that the transient features are more consistent with floating and/or suspended solids, bubbles, and waves than tides, sea level change, or seafloor change and based on the frequency of these phenomena in terrestrial settings, we consider waves to be the most probable hypothesis. These transient features are the first instance of active processes in Titan’s lakes and seas to be confirmed by multiple detections and demonstrate that Titan’s seas are not stagnant but rather dynamic environments.

Published
2016

48. Identification of buried lunar impact craters from GRAIL data and implications for the nearside maria

Author

Jason M. Soderblom, Jeffrey C. Andrews-Hanna, Alexander J. Evans, Maria T. Zuber, and Sean C. Solomon

Subjects
Basalt, Gravity (chemistry), 010504 meteorology & atmospheric sciences, Geochemistry, Crust, Geophysics, 01 natural sciences, Planetary science, Geology of the Moon, Impact crater, 0103 physical sciences, General Earth and Planetary Sciences, Density contrast, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences, Terrane
Abstract

Gravity observations from the dual Gravity Recovery and Interior Laboratory (GRAIL) spacecraft have revealed more than 100 quasi-circular mass anomalies, 26–300 km in diameter, on the lunar nearside. These anomalies are interpreted to be impact craters filled primarily by mare deposits, and their characteristics are consistent with those of impact structures that formed prior to, and during, intervals of flooding of feldspathic terrane by mare basalt lavas. We determine that mare deposits have an average density contrast of 850−200+300 kg m−3 relative to the surrounding crust. The presence of a large population of volcanically buried craters with minimal topographic expression and diameters up to 300 km requires an average nearside mare thickness of at least 1.5 km and local lenses of mare basalt as thick as ~7 km.

Published
2016

49. Tidal Currents Detected in Kraken Mare Straits from Cassini VIMS Sun Glitter Observations

Author

Jason W. Barnes, Jason M. Soderblom, Benoît Seignovert, Rajani D. Dhingra, Michael Heslar, and Christophe Sotin

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), geography, Bedform, geography.geographical_feature_category, Sun glitter, FOS: Physical sciences, Sediment, Astronomy and Astrophysics, Crust, Inlet, Seafloor spreading, Geophysics, Tectonic uplift, Oceanography, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Bathymetry, Geology, Astrophysics - Earth and Planetary Astrophysics
Abstract

We present Cassini VIMS observations of sun glitter -- wave-induced reflections from a liquid surface offset from a specular point -- on Kraken Mare. Sun glitter reveals rough sea surfaces around Kraken Mare, namely the coasts and narrow straits. The sun glitter observations indicate wave activity driven by the winds and tidal currents in Kraken Mare during northern summer. T104 Cassini VIMS observations show three sun glitter features in Bayta Fretum indicative of variegated wave fields. We cannot uniquely determine one source for the coastal Bayta waves, but we lean toward the interpretation of surface winds, because tidal currents should be too weak to generate capillary-gravity waves in Bayta Fretum. T105 and T110 observations reveal wave fields in the straits of Seldon Fretum, Lulworth Sinus, and Tunu Sinus that likely originate from the constriction of tidal currents. Coastlines of Bermoothes and Hufaidh Insulae adjoin rough sea surfaces, suggesting a complex interplay of wind-roughened seas and localized tidal currents. Bermoothes and Hufaidh Insulae may share characteristics of either the Torres Strait off Australia or the Aland region of Finland, summarized as an island-dense strait with shallow bathymetry that hosts complex surface circulation patterns. Hufaidh Insulae could host seafloor bedforms formed by tidal currents with an abundant sediment supply, similar to the Torres Strait. The coastlines of Hufaidh and Bermoothes Insulae likely host ria or flooded coastal inlets, suggesting the Insulae may be local peaks of primordial crust isolated by an episode of sea-level rise or tectonic uplift., Comment: Accepted to the Planetary Science Journal, 25 pages, 13 figures

Published
2020

50. Spatio-temporal Variation of Bright Ephemeral Features on Titan’s North Pole

Author

Rajani D. Dhingra, Jason W. Barnes, Christophe Sotin, Stéphane Le Mouélic, Robert H. Brown, Philip D. Nicholson, Jason M. Soderblom, Sebastien Rodriguez, Bonnie J. Buratti, Roger N. Clark, Kevin H. Baines, Michael Heslar, and Ralf Jaumann

Subjects
North pole, symbols.namesake, Geophysics, Space and Planetary Science, Ephemeral key, Earth and Planetary Sciences (miscellaneous), symbols, Astronomy and Astrophysics, Titan (rocket family), Atmospheric sciences, Geology
Abstract

We identify and document the instances of bright ephemeral features (BEF)—bright areas that appear, disappear, and shift from flyby to flyby on Titan’s north pole, using the Cassini Visual and Infrared Mapping Spectrometer data set, thereby developing a sense of their spatial distribution and temporal frequency. We find that BEFs have differing geographic location and spatial extents. However, they have similar observation geometries and orders of surface area coverage and are mostly accompanied by specular reflections. We find the BEFs to represent either broad specular reflection off of a recently wetted surface on the north pole of Titan or a near-surface fog—both owing to probable recent rainfalls. Our surface model constrains the surface roughness to be of 9°–15° indicating the approximate vertical relief of the region to be that of cobbles. We also find that within less than two Titan days the BEF (if on the surface) might infiltrate into the subsurface. We hypothesize the parts of BEFs that extend into the maria to be precipitation fog.

Published
2020

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